(a) Field of the Invention
The present invention relates to an inverter. More particularly, the present invention relates to a protection circuit of the inverter to supply power for driving a lamp.
(b) Description of the Related Art
In order to drive a discharge lamp, a high voltage is necessary, and an inverter is generally used in order to produce the high voltage. An inverter for driving the lamp transforms an input DC power source to an AC power source and supplies an AC voltage and an AC current to a discharge lamp. The inverter includes a transformer, a first side of the transformer is connected to a half- or a full-bridge circuit, and a second side of the transformer is connected to the lamp. The discharge lamp is driven by the AC voltage and the AC current generated at the second side. The inverter begins operating protection for safety and reliability of a lamp driver and the inverter when the lamp develops an open circuit or short circuit state. In detail, when the discharge lamp becomes an open circuit lamp, an output terminal of the inverter develops an open circuit state, and when the discharge lamp becomes a short circuit lamp, the output terminal of the inverter develops a short circuit state. The inverter senses feedback voltage and current knowing a state of the output terminal for a protection operation.
When the inverter includes a plurality of output terminals and a plurality of the output terminals are respectively connected to a plurality of lamps, the inverter must have outside elements corresponding to the number of lamps in order to detect an open circuit lamp or a short circuit lamp among the plurality of lamps. In detail, the inverter needs a plurality of feedback signals corresponding to a voltage and a current supplied to each of the plurality of lamps for a protection operation. The inverter includes outside elements such as diodes according to the number of the plurality of lamps in order to generate the plurality of feedback signals. Then, according to forming outside elements, the entire area of the inverter increases and manufacturing cost also increases.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.